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Discussion Starter · #1 · (Edited)
My wife's 2003 2.0 New Beetle has a recurring CEL relating to the engine coolant temperature. The OBDII scanner at AutoZone shows code P2181.

The first thing I replaced was the engine coolant temp sensor (black replaced with green). This solved the problem for a couple of weeks, then threw a code. I replaced the ect sensor again since it was so cheap and easy. Two weeks later, CEL. OK, we all know the definition of stupidity (doing the same thing expecting different results), so I replaced the sensor for the third time. This time it was two days for a CEL.

I then replaced the thermostat. The spring in the OEM thermostat seemed weak, so I thought it might be opening too soon and I had found the problem. WRONG! Two days after the new thermostat, another CEL.

I am disconnecting the battery to clear the CEL each time. The blue water temp light always goes out after a few minutes of driving. My wife says the CEL usually comes on in the morning as she accelerates up to speed on the interstate.

The guys over at the Audi A4 forum have a TSB from Audi that their problem is an auxillary radiator hose that has a faulty check (non-return) valve. They have a hose from the radiator to what they call an auxillary radiator. The check valve stays open preventing the coolant from reaching operating temperature which throws the CEL code 2181.

Question. Does the 2.0 Beetle have this auxillary radiator hose/non-return valve?

Any other ideas?
 

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180 Degrees out of faze
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Are you sure of the error code? A P2181 is not listed in any of my lists.
Could you get the codes read with a different scanner next time? It could be as case of chasing the wrong item.
 

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Discussion Starter · #3 ·
hannaco said:
Are you sure of the error code? A P2181 is not listed in any of my lists.
Could you get the codes read with a different scanner next time? It could be as case of chasing the wrong item.

This is an OBDII code, not a VW code. Code came from a generic OBDII scanner from AutoZone. The Audi guys who had the same code and took their cars to dealers had the dealers changing the same parts I changed multiple times until the TSB came out.

http://www.3800pro.com/lists/obd2codes.html
 

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I don't believe the 2.0 Beetle has the auxillary rad that the A4 guys are talking about. A couple other things I'd check would be the water pump (if you feel like it, you can pull the thermostat again and reach your fingers in and to the left through the thermostat hole - you can feel the impeller and will know if it's pooped). The only other thing that comes to mind is the coolant level sensor in the overflow bottle, but I didn't think it could throw a CEL, only make the coolant light flash red or something.
 

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Discussion Starter · #5 ·
rcy said:
I don't believe the 2.0 Beetle has the auxillary rad that the A4 guys are talking about. A couple other things I'd check would be the water pump (if you feel like it, you can pull the thermostat again and reach your fingers in and to the left through the thermostat hole - you can feel the impeller and will know if it's pooped). The only other thing that comes to mind is the coolant level sensor in the overflow bottle, but I didn't think it could throw a CEL, only make the coolant light flash red or something.
Thanks. I kind of figured the A4 was different. The coolant level sensor is OK because after the thermostat change the coolant level dropped when the thermostat opened up and the red coolant light flashed until I added more coolant.

I did not check the water pump impeller when I had the thermostat out. I did not realize it was there and I think the problem is that the engine is running too cool or the computer thinks it is. There is no temp guage on the New Beetle so it is hard to tell. The red water temp light does not indicate overheating.

The car is just out of warranty (54,000 miles) but I guess I'll have to take it to the dealer. Does the emissions warranty extend past 50,000 miles?
 

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Same problem p2181

I have the same problem on my 1.8t jetta. I have about the same amount of miles on my car and the MIL seems to come on at about the same time (about 10-15 minutes of morning driving on the freeway). I replaced the coolant temperature senson (only once) and still have the same problem...please update me on any solutions. Thanks, I'd love to get rid of this code (also have noticed a slight drop in gas milage).
 

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Discussion Starter · #7 ·
An update on my problem. I found one of the radiator fans was not working, I replaced it thinking that would stop the CEL. Nope, it came back. I bought VAG-COM which gave code "18613- Performance Malfunction in the Cooling System, P2181-35-10---Intermittent". Cleared the code and it returned.

So now I have replaced the black coolant sensor with new green sensors from VW (3 times!), replaced the thermostat, and replaced a bad radiator fan. I also cleaned the connection (plug) that attaches to the coolant sensor. I do not have a temp gauge, but the red overheating light has never come on. The blue light goes out when it warms up.

I decide to take it to the stealership without telling them anything except I have a CEL, to see what they say. So they tell me I have a bad coolant temp sensor! I then tell them I have replaced it multiple times, with no effect on the CEL. I ask the mechanic to look for TSB's and I look over his shoulder while he is on the computer. The recommended procedure if replacing coolant sensor and thermostat don't work, is to run electrical tests on the ECM when the engine is hot and when cold. The only thing left to do then is replace the ECM.

I told the mechanic I would trade the POS before I bought a new ECM. They let me leave without charging me for the diagnosis. Guess they felt sorry for me.

The car drives OK with the CEL, which it would not do initially. It ran OK before I did the repairs, but would be down on power if you gave it a lot of throttle. It may have sensed that a fan was not working and wouldn't give it full throttle. I'm just going to let my wife drive it with the CEL and check it once a week with the VAG-COM to make sure no other codes have tripped. My VW dealer sells Mitsubishi and Chevrolet, so I may trade it back to him for a non VW (after I clear the CEL) and let him fix it before he sells it (and just hope the sales manager doesn't talk to the service manager!)

Sorry for the long rant.
 

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BugABoo to you!!
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Any updates on this? My '03 is having the same issues.
 

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Discussion Starter · #9 ·
lilorangebug said:
Any updates on this? My '03 is having the same issues.
I traded the Beetle over a year ago on a new Civic. It still had the CEL when I traded it. The Civic, as expected, has been flawless.

It is too bad the Beetle was so poorly made mechanically (Plastic water pump, cheap radiator fan motors, plastic hose clips, etc.). The interior was solid and well made for an economy car. It was rattle free and the car rode and handled nicely. It was apparent that VW saved money inside the engine compartment.

Good luck.
 

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Thanks guys, this thread was help to me today, my daughters 2003 Beetle 2.0L had the P2181 Cooling System Performance ODBII code flagged, I had cleared it several times, after reading this thread,

1. Warmed up engine with my ScanGage II plugged in, this universal gage displays more than ODBII codes, it has gages and can display actual water temp. I could see the water temp change as the engine warmed. It warmed up to 197F and the fans never came on.

2. I turned on the Air Conditioner and both fans came on, this confirmed the fans were operational. So now I know the water temp sensor is reporting temp, and the fans work. I was also able to watch the temp as it climbed then it dropped suddenly (told me thermostat was working), so I rolled the dice and went to VW parts.

3. Without having the old part, the guy at the counter asked if I had the defective part, I said no. He then said you know if you buy the wrong part we cannot take it back? as it is electronic part. I said fine, give me the themoswitch for a 2003 Beetle. He hands me this Green Sensor, it has 4 conductors, I was expecting it to only have 3. So I was needing some other parts for the VW, and he was getting these and bagging them up. I said can you re-check this part? I was expecting it to only have 3 conductors and this has 4? He then says I asked for the wrong part, I said is this a thermo-switch? He says no it is a sensor, what did I ask for? He grudenly goes back to the computer screen and rounds up the right part and bags it. I hand him back the green sensor, don't think I need that yet. If the "switch" doesn't fix it, I'll come back and get the green one along with a water pump.

4. So I get home, have the VW on ramps, look for a 1-1/8" wrench or socket to fit that sucker, couldn't find one other than the collet wrench from my Porter Cable 690 Router, hey they fit that switch perfectly. Put a clear container under the radiator, remove the plug, use the 1-1/8" wrench to loosen the switch, out it comes about a pint of anti-freeze comes out, I screw in the new one. Plug it back in, take the clean contain that caught the lost antifreeze and used a funnel with a fine screen and poured the lost antifreeze back in the overflow.

5. Cleared the codes with the ScanGageII, started it up and allowed it to run for 20 minutes, temp started rising past 190F (according to ScanGage) and BOTH fans come on. Take it for a 5 mile drive and on the freeway, temp never got over 197F. Think I'm good to go for the time being.

Guess I got lucky picking the 1J0-959-481-A "Switch" at $49.23, and not letting the counter guy sell me the wrong part and going on a wild goose chase.

Thanks for your help guys!
 

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An update on my problem. I found one of the radiator fans was not working, I replaced it thinking that would stop the CEL. Nope, it came back. I bought VAG-COM which gave code "18613- Performance Malfunction in the Cooling System, P2181-35-10---Intermittent". Cleared the code and it returned.

So now I have replaced the black coolant sensor with new green sensors from VW (3 times!), replaced the thermostat, and replaced a bad radiator fan. I also cleaned the connection (plug) that attaches to the coolant sensor. I do not have a temp gauge, but the red overheating light has never come on. The blue light goes out when it warms up.

I decide to take it to the stealership without telling them anything except I have a CEL, to see what they say. So they tell me I have a bad coolant temp sensor! I then tell them I have replaced it multiple times, with no effect on the CEL. I ask the mechanic to look for TSB's and I look over his shoulder while he is on the computer. The recommended procedure if replacing coolant sensor and thermostat don't work, is to run electrical tests on the ECM when the engine is hot and when cold. The only thing left to do then is replace the ECM.

I told the mechanic I would trade the POS before I bought a new ECM. They let me leave without charging me for the diagnosis. Guess they felt sorry for me.

The car drives OK with the CEL, which it would not do initially. It ran OK before I did the repairs, but would be down on power if you gave it a lot of throttle. It may have sensed that a fan was not working and wouldn't give it full throttle. I'm just going to let my wife drive it with the CEL and check it once a week with the VAG-COM to make sure no other codes have tripped. My VW dealer sells Mitsubishi and Chevrolet, so I may trade it back to him for a non VW (after I clear the CEL) and let him fix it before he sells it (and just hope the sales manager doesn't talk to the service manager!)

Sorry for the long rant.
Here is what I heard from my repairman who has a friend on VW of America tech staff. (Yeh, I know....I don't know if I believe it either but, here goes.) The computer is set to throw a code if coolant temp is not up to design temp after a set amount of time. If it is cold and you need the defroster because it is AC it starts the fans immediately and does not allow coolant temp to rise fast enough to get to design temp in allotted time span. A simple solution would be to expand acceptable temp range. Problem. VW won't let you into that part of the computer. There are other things which cause same 'not in time' code throw.
 

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Same problem with my 03 NBC 2.0, Junior.

Dizzy, how is your thermoswitch working out for you? Any code since then?

Some background on my issue. When I clear the code, it always seems to come back on when I start from a cold engine and go right to highway driving, usually comes on as I'm accelerating up to speed. Doesn't come on in town--generally. Doesn't overheat, blue light comes on and then goes off after a respectable amount of time. Fans all work as they should (A/C force on or not). Thoughts, questions, suggestions? I haven't replaced anything at all yet.
 

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I had the same problem and replaced a bad theromastat, problem went away for about a month and back it came, for some reason I went and check the theromastat and quess what, it was bad again, don't get the failsafe ones, I finally went and got the real deal and it been 3 months now and no codes.
 

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I had the same problem. I found 1 more part to replace before the thermostat. On my 1.8T looking at the front of the car.
On the right hand side on the radiator there is a Y pipe for the coolant. There is a sensor right there. It looks like a coolant tempature sensor but it only has 2 connectors. I replaced this and my p2181 code has gone away. Not sure what the part is actually called.
 

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I had the same problem. I found 1 more part to replace before the thermostat. On my 1.8T looking at the front of the car.
On the right hand side on the radiator there is a Y pipe for the coolant. There is a sensor right there. It looks like a coolant tempature sensor but it only has 2 connectors. I replaced this and my p2181 code has gone away. Not sure what the part is actually called.
Do you have a part number? or where did you buy it?
 

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I just went to the dealer and they looked up the part. It was a special order though.

As with everyone with this code the saga continues. After a full week. After a hard stop on the freeway.... Same code back on. I am going to guess the real fix is going to just be a piece of electrical tape over it.
 

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I just went to the dealer and they looked up the part. It was a special order though.

As with everyone with this code the saga continues. After a full week. After a hard stop on the freeway.... Same code back on. I am going to guess the real fix is going to just be a piece of electrical tape over it.
Ahh, gotcha... dang that code/light... Best of luck...
 

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p2181

I had the same problem and replaced a bad theromastat, problem went away for about a month and back it came, for some reason I went and check the theromastat and quess what, it was bad again, don't get the failsafe ones, I finally went and got the real deal and it been 3 months now and no codes.
was your thermostat staying slightly open? what do you mean by failsafe thermostat?
 

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ok why didnt I see this thread a few months ago!

My 03 2.0L has the same issue / code. Replaced the coolent temp sensor (green one near top of engine) thinking that was it.

Same as everyone else, CEL stayed off a few weeks/months/days and then when leaving the gf's one morning jump on the interstate 2 mins from her house and BAM CEL again! Clear the code at least every other week at this point but its a PITA!

Also, since mine might be something else (going to stealer next weekend) but do you notice any mpg drops? Find one of my previous threads but Im STILL getting only about 250-300 miles per tank with mix of in town and hwy driving. My commute is 7 miles each way down 1 road (left out of the street i live on and then right into works parking lot -- reverse going home) 5 days a week and then light travel on the weekends and Im LUCKY if I get 250+ miles per tank (300 is a real stretch).

Only good saving grace to my mpg issues is its taking me less than $20 to fill up! (paid $1.46 per gallon last week)

Sorry I tend to ramble.... :D
 
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